Circuits used to provide connection between two nodes with different voltages include regulators which transfer power between the nodes in a controlled manner, hotswap circuits which join the two nodes together when the initial voltages are different, and surge suppression circuits which can protect one node from voltage surges on the other node. The two nodes typically have significant capacitance in any real circuit, which can cause very large currents to flow rapidly if the nodes are abruptly connected together. It takes some care to ensure that large transient voltage disturbances do not occur on the two nodes at the time when they are connected.
Circuits that provide connection between nodes often use dissipative elements. This typically requires a large switch device and a sophisticated controller that adjusts timing and slew rate to keep switch power dissipation within safe limits. This method maintains continuous current conduction at both the input and the output nodes during the connection event, which minimizes voltage disturbance at each node and devices that may be connected to these nodes. However, during the connection interval, significant power must be dissipated across the switch device. This causes the temperature of the switch device, such as a power transistor that may include a heat sink, to rise significantly during the connection event. The switching device must have an appropriate size to handle this temperature rise. At higher power levels, it may be difficult to find transistor devices that will work reliably.
Alternatively, a connection circuit may use a conventional buck regulator switching topology that limits current flow to safe levels by adjusting the duty cycle of the switching. This reduces power losses during the connection interval but causes the current at the input node to be discontinuous, which can disrupt or damage connectors and circuitry coupled to that node.
Therefore, there is a need for a new connection topology capable of minimizing power dissipation and providing continuous current conduction.